This invention relates to a high-frequency generator, comprising a multigrid electron tube including at least a grid pair consisting of a control grid and a screen grid, a power supply circuit and a load, the grid pair being coupled to the main current path of the electron tube, and comprising between the screen grid and the anode a feedback circuit for generating a high-frequency signal in the main current path of the electron tube.
Such a high-frequency generator, which finds application in industry, for example, in high-frequency heating, is widely known. In the known high-frequency generator the grid pair, that is to say the screen grid connected to a positive voltage, takes up current so that the efficiency of the power dissipated in the load remains relatively low. The absolute value of the power dissipated by the grid pair in the electron tube, which power does not go to the load, is considerable; especially in high-frequency generators for industrial applications which operate in the power range from several kilowatts to a number of megawatts. Owing to the heat dissipation in the electron tube, this power loss imposes constructional restrictions on the attainable compactness of the electron tube for such applications.